In the computer field, one of the many ways for the storage of data is in the form of magnetic tape. This tape is wound on supply and take-up reels and in a manner well known in the art, fed past a read-write head for reading data into the computer or for writing data from the computer.
In a typical tape-handler arrangement, the supply and take-up reels are mounted on hubs which rotate the reels in the desired manner under the control of an operator. Since tapes have only limited storage capacity, the operator must frequently remove the reels and replace them with others. The speed with which the operator can replace reels on the hub is an important factor in the efficient use of a computer system.
Various hubs for facilitating the rapid replacement of reels are presently in use. However, the structure of these hubs is complex compared to the hub of the present invention.
The present invention contemplates a hub of novel construction which, due to its few parts and simplicity of construction, makes for ease and economy of construction without sacrifice of durability and speed with which the reels may be mounted on and removed from the hub. Due to the simple design and few parts, the hub may be made from plastic material, making it lighter in weight which reduces reel-servo power requirements. In addition the construction of the present invention permits rapid disassembly and assembly for ease of maintenance and repair.
More specifically, the present invention comprises a circular-shaped baseplate and frontplate which fit together to form a circumferential surface about the outer periphery thereof on which a reel may be disposed. The baseplate and frontplate together form an annular V-shaped recess in the circumferential surface in which an O-ring is disposed. When the plates are moved to a first position relative to each other, the width of the V-shaped recess is made smaller to force the O-ring to expand axially beyond the circumferential surface to grip the inside surface of a reel and secure it to the hub. On moving the plates to a second position, the width of the V-shaped recess is made larger, permitting the O-ring to contract below the circumferential surface thereby releasing the hub. The means for moving the plates to the first and second positions comprises a shaft fixed to the backplate and extending therefrom. The frontplate has a handle having an opening in its center in which a two-position cam arrangement is disposed. The shaft extends into the cam arrangement and has a rod extending through it in the transverse direction for cooperation with the cam arrangement. When the handle is turned in a first direction, the rod is forced into one cam position moving the plates together to the first position. When the handle is turned in a second direction, the plates are moved away from each other to the second position. The baseplate has means for adjusting the length of the shaft for varying the gripping force of the hub.